Thermally actuated valve assembly

Claim 1

In a main valve assembly, such as for a fire extinguishing sprinkler, having a valve body with a main passage therethrough, one end of said main passage constituting an inlet adapted for connection to a pressurized fluid source and the other end thereof constituting an outlet adapted for the discharge of fluid, a main valve seat in said main passage between said inlet and said outlet, valve means movable between a closed position in engagement with said main valve seat blocking communication between said inlet and said outlet and an open position permitting the flow of fluid through said main passage, said main valve means having a first pressure area against which fluid pressure acts to move said valve means from its closed position to its open position and a second pressure area larger than the first pressure area against which fluid pressure acts to seat said valve means against said main valve seat so as to maintain said main valve means in its closed position against the force exerted by fluid pressure acting against said first pressure area, an auxiliary passage between said first pressure area and said second pressure area for equalizing fluid pressure applied to the first and second pressure areas, said auxiliary passage including a vent for venting fluid pressure from acting against said second pressure area; a thermally actuated pilot valve assembly for effecting opening of said main valve assembly in response to being subjected to a predetermined elevated ambient temperature, said pilot valve comprising a housing removably insertable as a unit into said valve body in said auxiliary passage between said second pressure area and said vent, a pilot valve passage in said valve housing consituting a portion of said auxiliary passage through which all fluid vented from said vent port must flow, said pilot valve passage having an inlet, an outlet and a valve seat therebetween, said pilot valve assembly further comprising a pilot valve member movable in said pilot valve housing between a closed position in which said pilot valve member is seated in said pilot valve thereby to block communication between said second pressure area in said vent so as to maintain fluid pressure acting against said second pressure area and to maintain said main valve means in its closed position and an open position for venting fluid pressure from said auxiliary passage thus reducing the fluid pressure acting against the second pressure area so as to enable fluid pressure acting against the first pressure area to open said main valve means, means for biasing said pilot valve towards its closed position, a thermostatic disk carried by said pilot valve housing, said disk being abruptly movable over center from a first curvature position to a second curvature position when subjected to said predetermined ambient temperature, means interconnecting said disk and said pilot valve member, and abutment means spaced from said disk when the latter is in its first curvature position and engageable by said disk as it moves From its first to its second curvature position thereby to permit free movement of said disk until it engages said abutment means without application of force to said pilot valve member and, upon engagement of the disk by said abutment means, to apply a force to said pilot valve member via said interconnecting means so as to move it against the force of said biasing means toward its open position.